## Posts tagged ‘sales rank’

### Dead Man’s Hand

A few days ago, I posted about the repeating digits that had been occurring in the Amazon sales rank of *Math Jokes 4 Mathy Folks*. For three days in a row, a repeating digit occurred three times in the sales rank each day.

The story continues.

On August 1, it happened again… but something cooler happened, too. The sales rank of *MJ4MF* on August 1 was 88,111. Though sad in regards to book sales, it’s numerically fantastic! Not only does it contain a digit that repeats three times (1), the other digit (8) repeats twice, and — hold on to your hat! — the repeated digits 8 and 1 occurred on the date 8/1!

Does it get any cooler than that?

Well, maybe. It might have been a little cooler if the rank were 8,111, which would match the full date 8/1/11.

But 88,111 could also be thought to represent a “Dead Man’s Hand” in poker. Officially, a Dead Man’s Hand contains a pair of aces and a pair of eights, but many sources also use the term to refer to a full house with aces over eights.

What did the geometrician say when someone took his playing cards?

Decagon.

This reminds me of a poker game that I played with an engineer and a statistician. In the middle of the second hand, the police raided the game. An officer asked the engineer, “Were you gambling?”

The engineer replied, “No, officer, I was not gambling.”

The officer then asked the statistician, “What about you?”

The statistician replied, “No, officer, I was not gambling, either.”

Finally, the officer turned to me. “Were you gambling?” he asked.

I replied, “By myself?”

### Coming Up Through the Ranks

Through some special features at Amazon Author Central, I am able to know the daily sales rank of Math Jokes 4 Mathy Folks. My sales rank at the end of each of the last three days was 44,404, 96,990, and 35,355, respectively. I thought that was interesting — three days in a row when the sales rank was a five-digit number in which one digit occurred at least three times. What’s the likelihood of that? Stated more formally:

Assuming that the sales rank of MJ4MF is always a five-digit number, what is the probability that three consecutive days’ sales ranks will contain a digit that occurs in the sales rank at least three times?

The sales rank of MJ4MF has never been a five-digit number in which the same digit is repeated five times. (Bummer!) The probability of that occurrence, though, is even less likely than the situation described above — though I won’t tell you exactly how much less likely, so as not to spoil your fun!